1) Field of the Invention
This invention relates to a subscriber terminating equipment suitable for use with a subscriber accommodation system.
2) Description of the Related Art
As a result of remarkable increase in demand for communication in recent years, it is requested for local exchange carriers and so forth to achieve stable signal transmission between subscriber terminals and an exchange, a router or a like equipment.
A signal transmitted from a subscriber terminal is inputted to a subscriber terminating equipment using a metallic subscriber line and terminated by the subscriber terminating equipment. Then, the signal is connected to a network interface apparatus such as an exchange, a router or the like and transmitted to a network interface apparatus of its destination.
In such a communication system as just described, when the subscriber terminating equipment fails or when the subscriber terminating equipment is stopped in order to perform maintenance, checking or the like of it, accommodation subscribers therein must be temporarily moved to another subscriber terminating equipment to perform services to them. For example, in order to perform replacement of a package, subscriber terminals accommodated in the failed package cannot enjoy services until the failed package is replaced.
Accordingly, in order to perform temporary accommodation (temporary relief) during failure of a package or temporarily switching to reserved circuits upon replacement (exchanging) of a package, a relief package (subscriber terminating package for relief) for accommodating reserved circuits is provided in advance.
When such subscriber accommodation or temporary switching is performed by switching the circuits by means of switches, the prepared relief package is used to perform the switching of the switches between the subscribers and the network interface fully automatically (by unattended remote operation) through the switching of a minimum but necessary number of switches and increase of a minimum but necessary number of wiring lines.
FIG. 44 is a diagram showing an example of a system construction of a communication network. Referring to FIG. 44, the communication network 96 shown includes a plurality of subscriber terminals (network terminals; a network terminal (NT) may sometimes be referred to simply as terminal) 70-1 to 70-n and 76-1 to 76-n, a plurality of subscriber lines 81-1 to 81-n and 82-1 to 82-n, subscriber terminating equipments 71 and 75, network interface apparatus 72 and 74, and a network 73. Each of the network interface apparatus 72 and 74 is formed from an exchange, a router or a like equipment and exhibits functions of the same.
A signal from any of the subscriber terminals 70-1 to 70-n is transmitted from the network interface apparatus 72 to the network 73 after an electric connection path therefor is set by the subscriber terminating equipment 71. Also a signal from the network 73 is transmitted in a similar manner to any of the subscriber terminals 76-1 to 76-n.
FIG. 45 is a detailed block diagram of the subscriber terminating equipment 71. Referring to FIG. 45, the subscriber terminating equipment 71 shown includes a plurality of subscriber terminating packages LT#1 to LT#n for connecting/disconnecting the plurality of subscriber terminals 70-1 to 70-n, and a relief package LT#RS.
Each subscriber terminating package LT#i (i is a natural number from 1 to n) individually performs line termination and circuit termination in order to allow the subscriber lines 81-i to be accommodated in the network interface apparatus 72 and includes a subscriber connection/relief switch 85-i and a subscriber circuit 84-i.
Meanwhile, the relief package LT#RS is provided to relieve subscribers accommodated in any of the subscriber terminating packages LT#i when a fault occurs with the subscriber terminating package LT#i (such package is hereinafter referred to as fault package). The relief package LT#RS includes a subscriber connection/relief switch 85-RS and a subscriber circuit 84-RS similarly to the subscriber terminating packages LT#i.
The subscriber connection/relief switch 85-i connects/disconnects the subscriber line 81-i from the subscriber terminal 70-i and performs, when a fault occurs, path switching from the fault package LT#i to the relief package LT#RS and other necessary operation.
The subscriber circuit 84-i processes a signal from the subscriber terminal 70-i connected by the subscriber connection/relief switch 85-i and includes a four-line/two-line conversion circuit 86, a transmission circuit (transmission driver) 87a, a reception circuit (receiver) 87b, a line terminating circuit section 88, a circuit terminating circuit section 89 and an interface section 90.
The four-line/two-line conversion circuit 86 converts a signal transmitted in balance from the subscriber connection/relief switch 85-i into a four-line signal (or vice versa). The transmission circuit 87a transmits the transmission signal produced by the line terminating circuit section 88 to output it to the subscriber line 81-i. The reception circuit 87b receives a signal transmitted thereto from the subscriber terminal 70-i over the subscriber line 81-i through the four-line/two-line conversion circuit 86 and outputs the signal to the line terminating circuit section 88.
The line terminating circuit section 88 shapes the waveform of a signal, which has passed through and thereupon been attenuated and distorted by the subscriber line 81-i, and amplifies the signal of the shaped waveform and extracts a clock signal from the transmission data. In particular, since deterioration attenuation and distortion occur with the transmission data of a digital signal while it is transmitted along a line, the line terminating circuit section 88 shapes the waveform of the transmission data and outputs resulting data to the circuit terminating circuit section 89.
The circuit terminating circuit section 89 performs signal termination processing such as frame synchronizing processing of transmission data, addition/extraction of a signal for transmission of control or information, and error correction. The circuit terminating circuit section 89 performs the signal termination processing by digital processing.
The interface section 90 converts the format for use with the subscriber terminating equipment 71 into another format for allowing the data to be handled by the network interface apparatus 72.
Thus, the subscriber terminal 70-i is physically connected by the subscriber connection/relief switch 85-i, and conversion of a signal from a 2-line signal into a 4-line signal is performed by the four-line/two-line conversion circuit 86. Then, the reception signal is received by the reception circuit 87b, and waveform shaping and amplification of the signal, which has been attenuated and distorted during transmission thereof over the subscriber circuit, are performed by the line terminating circuit section 88. Then, frame processing and so forth of the signal are performed by the circuit terminating circuit section 89. Thereafter, the signal is converted into a signal of the format for use with the network interface apparatus 72 by the interface section 90 and then transmitted to the network interface apparatus 72.
On the other hand, a signal from the network interface apparatus 72 is converted into a signal of the predetermined format by the interface section 90, and frame processing is performed for the signal by the circuit terminating circuit section 89. Then, waveform shaping (conversion) suitable for the signal to be outputted to the subscriber lines 81-i is performed for the signal from the circuit terminating circuit section 89 by the line terminating circuit section 88. Further, the signal is converted from a four-line signal into a two-line signal by the four-line/two-line conversion circuit 86. Then, the two-line signal is transmitted from the subscriber connection/relief switch 85-i to the subscriber terminal 70-i over the subscriber line 81-i.
As a countermeasure against a possible failure (fault), doubling or some other measures are taken for the line from the network 73 to the subscriber terminating equipment 71 in FIG. 44. However, the subscriber terminals 70-i and the subscriber lines 81-i which are connected between the subscriber terminating equipment 71 and the subscriber terminals 70-i are provided usually in a one-by-one connection scheme and therefore require a very high cost if such fault countermeasure as doubling is taken. Therefore, doubling of the subscriber lines 81-i is not used popularly.
Therefore, while disconnection of the subscriber lines 81-1 to 81-n themselves between the subscriber terminals 70-1 to 70-n and the subscriber terminating equipment 71 shown in FIG. 46 cannot be avoided, if a fault occurs with any one subscriber terminating package LT#i in the subscriber terminating packages LT#1 to LT#n shown in FIG. 47, for example, with the subscriber terminating packages LT#1, then the destination of the subscriber terminal 70-1 accommodated in the subscriber terminating package LT#1 with which the fault has occurred is switched to the relief package LT#RS to relieve the subscriber terminal 70-1 which has been accommodated in the fault package LT#1.
In order to switch a circuit when a fault occurs, the subscriber terminating equipment 71 can be constructed and the circuit switching by the subscriber terminating equipment 71 can be performed in the following three manners or methods (i) to (iii).
(i) Only Temporary Relief when a Fault Occurs is Performed without Using a Switch Package for Exclusive Use for Switching (First Method)
FIG. 48 is a diagrammatic view illustrating a connection scheme of subscriber terminals 101-1-1 to 101-n-1 in the subscriber terminating equipment 71 in a normal state. Referring to FIG. 48, the subscriber terminating equipment 71 includes a plurality of subscriber terminating packages LT#1 to LT#n and a multi-connection line 104-1 by which the subscriber terminating packages LT#1 to LT#n are connected to each other.
It is to be noted that, in FIG. 48, elements only for the channel 1 are shown. However, since elements for the other channels 2 to n are similar to those for the channel 1, overlapping illustration in FIG. 48 and overlapping description herein of them are omitted to avoid redundancy.
FIG. 49 is a schematic diagrammatic view of the subscriber terminating equipment 71. Referring to FIG. 49, the subscriber terminating equipment 71 shown includes a backboard 301 serving as a back plate, and a plurality of subscriber terminating packages LT#1 to LT#n and a relief package LT#RS each in the form of a board, all accommodated in an equipment frame 300 in the form of a box. Each channel of the subscriber terminating packages LT#1 to LT#n and the relief package LT#RS includes subscriber terminating circuit LT#i-1 to LT#i-m (m is a natural number) and relief packages LT#RS-1 to LT#RS-m.
In particular, each of the subscriber terminating packages LT#i and the relief package LT#RS includes a plurality of subscriber terminating circuits LT#i-j (j is a natural number from 1 to m) or LT#RS-j and each subscriber terminating circuit LT#i-j or LT#RS-j can accommodate subscriber terminals 101-i-j.
Each of the subscriber terminating packages LT#i and the relief package LT#RS can be removed from or inserted into the backboard 301 of the subscriber terminating equipment 71 if a fault occurs therewith or in a like case. If a fault occurs with the subscriber terminating circuit LT#i-j, then the subscriber terminating package LT#i with which the fault occurs can be replaced by an operator.
Each of the subscriber terminating circuits LT#1-1 and LT#RS-1 includes a subscriber connection switch (SW-L switch) 105-1-1 and a multi-connection switch (SW-M switch) 106-1-1 as shown in FIG. 48.
The subscriber connection switch 105-1-1 is connected to a subscriber line 103-1-1 from the subscriber terminal 101-1-1 and connects or disconnects the subscriber terminal 101-1-1.
Meanwhile, the multi-connection switch 106-1-1 is provided to switch, when a fault occurs with the subscriber terminating package LT#1 to which it belongs, the path from the subscriber terminal 101-1-1 to the relief package LT#RS. One end of the multi-connection switch 106-1-1 is connected to the subscriber line 103-1-1 to which it belongs while the other end of the multi-connection switch 106-1-1 is connected to the multi-connection switches 106-2-1 to 106-n-1 of the other subscriber terminating packages LT#2 to LT#n and the SW-M switch 106-RS-1 of the relief package LT#RS.
Also the other subscriber terminating packages LT#2 to LT#n are connected in a similar manner to the subscriber terminating package LT#1 as described above.
Thus, the subscriber connection switches 105-1-1 to 105-n-1 shown in FIG. 48 are set to a connection state (on) and the multi-connection switches 106-1-1 to 106-n-1 are set to a disconnection state (off) so that signals from the subscriber terminals 101-1-1 to 101-n-1 are connected to a common section 99 through the subscriber connection switches 105-1-1 to 105-n-1 of the corresponding subscriber terminating circuits LT#i-j, respectively. Accordingly, normal transmission is performed along signal paths indicated by thick lines in FIG. 48.
Then, if a fault occurs with the subscriber terminating circuit LT#1-1 (refer to a screened portion in FIG. 50), then the SW-L switch 105-1-1 of the subscriber terminating circuit LT#1-1 of the fault package LT#1 which has the subscriber terminating circuit LT#1-1 is switched off and the SW-M switch 106-1-1 is switched on. Further, the SW-M switch 106-1-1 is switched on, and the SW-M switch 106-RS-1 and the SW-L switch 105-RS-1 of the subscriber terminating circuit LT#RS-1 of the relief package LT#RS are switched on. Consequently, the subscriber terminal 101-1-1 which has been accommodated in the subscriber terminating circuit LT#1-1 is relieved by the subscriber terminating circuit LT#RS-1 of the relief package LT#RS.
As described hereinabove, each of the subscriber terminating packages LT#i and the relief package LT#RS has subscriber terminating circuits LT#i-j for a plurality of channels. Further, each of the subscriber terminating circuits LT#i-j and LT#RS-j has an SW-L switch (refer to the reference character 105-i-j of FIG. 48) and an SW-M switch (refer to the reference character 106-i-j of FIG. 48) shown in FIG. 51 and are connected to one another by a multi-connection line (refer to reference character 104-1 of FIG. 48). Thus, each of the subscriber terminating circuits LT#i-1 and LT#RS-1 operates similarly to the subscriber terminating circuits LT#i-1 and LT#RS-1 of the channel 1.
It is to be noted that, in FIG. 51, each arrow mark indicates a direction of connection. Further, while such arrow marks are omitted for the other channels 2 to m, they are similar to those of the channel 1. Thus, the subscriber terminating packages LT#i are relieved for each channel.
In this instance, however, if the operator removes the fault package LT#1 in order to replace it, since a path for bypassing (path upon relief) passes in the fault package LT#1 to be removed, the communication is interrupted.
(ii) Method which Uses an External Connection Cable (Second Method)
FIGS. 52 to 54 are diagrammatic views illustrating operation of the method which uses an external connection cable. Particularly, FIG. 52 illustrates normal operation of the method. Referring to FIG. 52, similarly as in the method wherein only temporary relief upon fault is performed without using a switch package for exclusive use for switching, the subscriber terminating equipment 71 includes a plurality of subscriber terminating packages LT#1 to LT#n, a relief package LT#RS, and a multi-connection line 104-1 as well as a switch package LT#SW.
The switch package LT#SW includes a temporary relief switch (SW-PR) 108-1 and an SW-RS switch 109-1-1. The temporary relief switch 108-1 is connected to multi-connection switches 106-1-1 to 106-n-1 of the subscriber terminating circuit LT#1-1 and an SW-M switch 106-RS-1 of the subscriber terminating circuit LT#RS-1 of the relief package LT#RS by the multi-connection line 104-1.
If the subscriber terminating circuit LT#1-1 shown in FIG. 53 fails, then the subscriber terminating equipment 71 controls so that the SW-L switch 105-1-1 of the subscriber terminating circuit LT#1-1 of the failed package LT#1 is switched off and the SW-M switch 106-1-1 is switched on while the SW-L switch 105-RS-1 and the SW-M switch 106-RS-1 of the subscriber terminating circuit LT#RS-1 of the relief package LT#RS are switched on. Accordingly, a signal from the subscriber terminal 101-1-1 accommodated in the failed package LT#1 is introduced into and temporarily relieved by the relief package LT#RS.
Here, since the path switching upon temporary relief measure is performed using the SW-M switch 106-1-1 of the fault package LT#1, if replacement of the fault package LT#1 is performed directly in this state, then the path for relief is interrupted similarly as with the first method.
Therefore, the subscriber terminating equipment 71 shown in FIGS. 55(a) and 55(b) includes a connector for external connection provided on the equipment frame (BWB) thereof so that any of the subscriber terminating packages LT#1 to LT#n and the switch package LT#SW can be connected to each other using an external connection cable 107.
The length of the external connection cable 107 is set based on the distance between the switch package LT#SW and that one of the subscriber terminating packages LT#i which provides the greatest distance from the switch package LT#SW so that the external connection cable 107 can connect any of the subscriber terminating packages LT#1 to LT#n to the switch package LT#SW.
When the fault package LT#1 shown in FIG. 54 is to be replaced, in order to extract a relief path from within the fault package LT#1, the operator will perform manual operation to connect the fault package LT#1 and the switch package LT#SW using the external connection cable 107 and switch the SW-M switch 106-1-1 of the subscriber terminating circuit LT#1-1 of the fault package LT#1 off and switch the SW-RS switch 109-1 of the switch package LT#SW on and further switch the temporary SW-PR switch 108-1 of the switch package LT#SW off. Consequently, as seen from a path indicated by a thick line in FIG. 54, a signal from the subscriber terminal 101-1-1 is connected to the relief package LT#RS without passing the fault package LT#1.
Accordingly, even if the fault package is removed, the relief path is not interrupted at all. Consequently, the fault package LT#1 can be replaced without interruption of communication of the relieved subscriber.
It is to be noted that, also in this instance, the subscriber terminating packages LT#1 to LT#n, the relief package LT#RS and the switch package LT#SW shown in FIG. 56 have switches similar to those for the channel 1 also for the channels 2 to m. Also the switches for the channels 2 to m operate similarly to those for the channel 1.
In this instance, however, since the operator connects a connector of the switch package LT#SW and a connector of the fault package LT#1 on the equipment frame 300 by manual operation, connectors which can be connected to each other physically and so forth are required. Further, since the external connection cable 107 is connected by manual operation, connection in error, incomplete connection or the like occurs likely.
Further, for the external connection cable 107, a single external connection cable having a wiring line length of a ((margin for connection operation)+(package numberxe2x88x921)xc3x97(thickness of package)) may be prepared. However, there is the possibility that soiling, dust or the like may cause incomplete connection of a connector. Further, depending upon the position of the subscriber terminating package LT#i, when a fault occurs, deterioration in characteristic may possibly occur because the wiring line length of the external connection cable 107 is excessively long.
(iii) Method wherein Wiring Lines Corresponding to an External Connection Cable Are Wired in Advance on the Backboard (Third Method)
This method is a modification to the second method, and according to the present method, wiring lines corresponding to the external connection cable 107 are wired in advance between the subscriber terminating packages LT#i and the switch package LT#SW and are switched by means of a switch in the switch package LT#SW.
Referring to FIGS. 57 to 59, the subscriber terminating equipment 71 shown is different from the subscriber terminating equipment 71 of the second method in that it includes SW-RS switches 109-1-1 to 109-n-1 provided corresponding to the subscriber terminating packages LT#1 to LT#n in the switch package LT#SW and wiring lines (jumper wiring lines) 110-1-1 to 110-n-1 which correspond to the external connection cable 107 are wired between the subscriber terminating packages LT#i and the switch package LT#SW in advance.
When the subscriber terminating equipment 71 operates normally as seen in FIG. 57, similarly as in the second method, the SW-L switches 105-1-1 to 105-n-1 of the subscriber terminating packages LT#1 to LT#n are set to an on-state while the SW-M switches 106-1-1 to 106-n-1 are set to an off-state in accordance with a control signal from the outside. Consequently, signals from the subscriber terminals 101-1-1 to 101-n-1 are individually transmitted along paths indicated by thick lines in FIG. 57.
Then, if the subscriber terminating package LT#1 shown in FIG. 58 fails, then similarly as in the methods described in the paragraphs (i) and (ii) above, the subscriber terminating equipment 71 controls the subscriber connection switch 105-1-1 of the subscriber terminating circuit LT#1-1 of the fault package LT#1 to an off-state and controls the SW-M switch 106-1-1 of the subscriber terminating circuit LT#1-1 to an on-state, and further controls the SW-L switch 105-RS-1 of the relief package LT#RS to an on-state and controls the SW-PR switch 108-1-1 of the-switch package LT#SW to an on-state. Consequently, relief of the fault package is performed through paths of thick lines in FIG. 58. It is to be noted that such operation as illustrated in FIG. 58 is called temporary relief.
When the fault package LT#1 shown in FIG. 59 is to be replaced, the SW-RS switch 109-1-1 of the switch package LT#SW corresponding to the fault package LT#1 is switched on and the SW-PR switch 108-1 is switched off. Consequently, a signal from the subscriber terminal 101-1-1 is transmitted to the relief package LT#RS through the switch package LT#SW and thus follows such a path as indicated by a thick line in FIG. 59. Such operation as seen in FIG. 59 is called reserved switching.
FIG. 60 is a diagrammatic view illustrating flows of signals where a plurality of channels are used in the subscriber terminating equipment 71. Also in this instance, the subscriber terminating equipment 71 performs operation for the channels 2 to m similar to that for the channel 1.
Further, in the present method, the processing for the reserved relief is not necessarily required, and when a fault occurs, only processing for the temporary switching may be performed. Since switching to the relief package LT#RS is performed without using a switch in the fault package LT#1, communication is not interrupted also when the subscriber terminating package LT#1 is replaced.
This method, however, requires the switch package LT#SW for exclusive use and further requires a complicated wiring scheme.
Such subscriber terminating circuits of (i) to (iii) as described above have the following subjects.
(1) Subject to the Method wherein Only Temporary Relief Upon Fault Is Performed Without Using a Switch Package for Exclusive Use for Switching
The method of (i) has a subject in that, as described hereinabove, if a fault package LT#i is removed in order to replace it, then since the bypassing path (path upon relief) passes in the fault package to be removed, communication is interrupted.
(2) Subject to the Method wherein an External Connection Cable Is Used
Also the method of (ii) requires physically connectable connectors, the external connection cable 107 and so forth on the outside of the subscriber terminating packages LT#i and the relief package LT#RS.
Further, for replacement of the fault package LT#1, an operator who performs the operation is required at a site for operation, and there is the possibility that an artificial miss such as wrong connection or incomplete connection of the external connection cable 107 may take place.
Furthermore, the external connection cable 107 for mere connection must be stored and managed in the proximity of the equipment, and besides there is the possibility that deterioration in characteristic may be caused by deterioration of a marginal portion of the external connection cable 107.
Besides, the external connection cable must be stored and managed in the proximity of the equipment and occupies a space of an equipment frame, and it is difficult to keep the security of the wiring lines.
Also it is a subject that the switch package LT#SW for exclusive use is required.
(3) Subjects to the Method wherein Wiring Lines Corresponding to an External Connection Cable Are Wired in Advance on a Backboard
In the method of (iii), the circuit construction is complicated as described above. Further, since an increased wiring line length is required, the wiring lines are complicated when subscriber lines and the subscriber terminating circuit LT#i-j are connected to each other and become liable to suffer from an influence which causes deterioration in characteristic such as crosstalk.
Further, while an increased number of subscriber lines are wired on the backboard, since there are limitations to the number of switches which can be mounted on the switch package LT#SW, the number of subscriber lines which can be connected to the connectors and the number of subscribers which can be accommodated, the method of (iii) can be applied only to a limited number of subscriber apparatus.
Furthermore, where the distance from the subscriber terminating packages LT#i to the switch package LT#SW is great, since the wiring line length between them is added to the subscriber line 103-i-j, there is the possibility that this may give rise to deterioration in characteristic.
Further, since a great number of wiring lines are laid over long distances on the backboard, there is a high degree of possibility that noise may be provided to another signal system or noise may be provided from another signal system.
Also it is a subject that an increased cost is required.
The subscriber terminating equipments 71 of the methods (i) to (iii) described above, however, cannot solve all of such subjects as described above simultaneously.
It is an object of the present invention to provide a subscriber terminating equipment wherein switching operation of a circuit upon fault can be performed fully automatically.
It is another object of the present invention to provide a subscriber terminating equipment wherein, when a fault occurs with a subscriber terminating package, it can be replaced without disconnection of a circuit.
It is a further object of the present invention to provide a subscriber terminating equipment which is simplified in circuit configuration and wiring scheme.
In order to attain the object described above, according to an aspect of the present invention, there is provided a subscriber terminating equipment which includes a plurality of subscriber terminating packages connected between a plurality of subscriber terminals side and a network interface apparatus side, the network interface apparatus being connected to a network and capable of transferring a signal to a desired destination for accommodating the subscriber terminals, and a relief package having the same construction as that of the plurality of subscriber terminating packages for accommodating the subscriber terminals accommodated in a fault package which has failed from among the plurality of subscriber terminating packages, comprising a multi-connection line disposed in the proximity of the plurality of subscriber terminals and connected to each of the plurality of subscriber terminating packages, and a common section connected to each of the plurality of subscriber terminating packages for outputting switching signals to perform switching of a path between the subscriber terminals and the network interface apparatus, the plurality of subscriber terminating packages including multi-connection switches connected to the subscriber terminals and the multi-connection line for connecting/disconnecting electric signals between the subscriber terminals and the multi-connection line, subscriber connection switches connected to the subscriber terminals for connecting/disconnecting electric signals between the subscriber terminals and the network interface apparatus in response to connection conditions of the multi-connection switches, and relief switches connected to the subscriber connection switches, the relief package including a relief switch connected to the multi-connection line for connecting/disconnecting an electric signal between the multi-connection line and the network interface apparatus, a subscriber connection switch connected to the relief switch, and a multi-connection switch provided on a circuit board or a plurality of circuit boards, the common section selecting a pair of packages including a first package and a second package from among the plurality of subscriber terminating packages and allocating, if the first package fails, the second package as a bypass package for performing electric connection between the subscriber terminals and the relief package, the relief package and the subscriber terminating packages having the same circuit pattern for connection of the three kinds of switches.
In the subscriber terminating equipment, if a fault occurs with any one of the first and second subscriber terminating packages, the other of them functions as a bypass package for the one subscriber terminating package in accordance with switching signals from the common section and automatically accommodates the subscriber terminals of the fault package without passing the inside of the fault package. Consequently, the fault package can be replaced without disconnecting communication of the subscriber lines which have been accommodated in the fault package, and the circuit construction and the wiring line scheme can be simplified. Further, the subscriber terminating packages and the relief package can be formed with the same circuit configuration. Consequently, there is an advantage that reduction of the production cost can be anticipated because the number of parts can be reduced upon manufacture of the packages.
The common section may be constructed such that it controls, in normal operation, the subscriber connection switches in the subscriber terminating packages to a connection state and controls the three kinds of switches in the relief package to a disconnection state, but connects, when failure occurs, the subscriber terminals accommodated in the fault package with which the fault has occurred to the network interface apparatus through the multi-connection line and the bypass package.
As an alternative, the common section may be constructed such that it controls, when a fault occurs, the subscriber connection switch in the fault package to a disconnection state, controls the multi-connection switch in the bypass package to a connection state and controls the relief switch of the relief package to a connection state.
In the subscriber terminating equipments, if a fault occurs with any of the subscriber terminating packages, the subscriber terminals accommodated in the fault package are connected to the relief package without passing through the fault package. Consequently, there is an advantage that replacement of the fault package can be performed without disconnection of communication.
As another alternative, the common section may be constructed such that it allocates, when a fault occurs, one of the subscriber terminating packages which is adjacent the fault package as the bypass package, and sets the subscriber connection switch in the fault package to a disconnection state, sets the multi-connection switch in the bypass package to a connection state and controls the relief switch in the relief package to a connection state.
In the subscriber terminal equipment, if a fault occurs with any of the subscriber terminating packages, the subscriber terminals accommodated in the fault package are connected to the relief package without passing through the fault package. Consequently, even if the fault package is removed for replacement, communication is not disconnected, and accordingly, there is an advantage that the stability of the system is augmented.
As a further alternative, the common section may be constructed such that it selects one of the subscriber terminating packages which is disposed on the right side of the fault package and allocates the selected subscriber terminating package as the bypass package. Otherwise, the common section may be constructed such that it selects one of the subscriber terminating packages which is disposed on the left side of the fault package and allocates the selected subscriber terminating package as the bypass package.
In the subscriber terminating equipments, since a subscriber terminating package which is adjacent the fault package is allocated as a bypass package for it, the wiring lines are shortened and simplified. Consequently, there is an advantage that the transfer characteristic is augmented.
Otherwise, the common section may be constructed such that it establishes, when failure occurs, a self relief mode wherein the multi-connection switch in the fault package is set to a connection state and the subscriber connection switch and the multi-connection switch in the relief package are set to a connection state.
The subscriber terminating equipment is advantageous in that, when a fault occurs, the subscriber terminals can be relieved without the necessity for a package for bypassing.
Further, the common section may establish, when a fault occurs, a circuit switching mode wherein the three kinds of switches at least in the fault package are set to a disconnection state and the subscriber connection switch and the relief switch in the adjacent subscriber terminating package are set to a disconnection state while the multi-connection switch and the subscriber connection switch in the relief package are set to a connection state.
The subscriber terminating equipment is advantageous in that, since the circuit switching mode is set when a fault occurs, the fault package can be replaced without disconnection of communication of any of the subscriber terminals accommodated in the fault package.
Alternatively, the common section may establish, when a fault occurs, a self relief mode wherein the multi-connection switch at least in the fault package is set to a connection state and the subscriber connection switch in the fault package is set to a disconnection state while the subscriber connection switch in the adjacent subscriber terminating package is set to a connection state and the multi-connection switch and the subscriber connection switch in the relief package are set to a connection state.
The subscriber terminating equipment is advantageous in that, when a fault occurs, the subscriber terminals can be relieved without the necessity for a package for bypassing.
Otherwise, the common section establishes, when a fault occurs, a circuit switching mode wherein the three kinds of switches at least in the fault package are set to a disconnection state and the subscriber connection switch and the relief switch in the adjacent subscriber terminating package are set to a disconnection state while the multi-connection switch in the relief package is set to a connection state.
In the subscriber terminating equipment, the subscriber terminals accommodated in the fault package are connected to the relief package without passing through the switches in the fault package. Consequently, there is an advantage that, also when the fault package is replaced, it can be replaced without disconnection of communication of the subscriber terminals.
The packages may be formed such that at least ones of L/M points indicative of connection points of the subscriber terminals and the multi-connection switches, M/RS points indicative of connection points between the multi-connection line and the relief switches and RS/L points indicative of connection points between the relief switches and the subscriber connection switches are provided outside the subscriber terminating packages.
With the subscriber terminating equipment, there is an advantage that the number of circuit patterns for the subscriber terminating packages and the relief package can be reduced upon manufacture of the subscriber terminating packages and the relief package. Further, where the connection points are provided within the subscriber terminating packages, the wiring line lengths are reduced. Consequently, there is an advantage that the transmission characteristic can be augmented.
The subscriber terminating packages and the subscriber terminals may communicate with each other using a communication system which employs a two-line type subscriber line. Alternatively, the subscriber terminating packages, the subscriber terminals and the network interface apparatus may communicate with each other using a communication system which employs a four-line type subscriber line.
The subscriber terminating equipment is advantageous in that it can be applied irrespective of the transmission system used.
According to another aspect of the present invention, there is provided a subscriber terminating equipment which includes a plurality of subscriber terminating packages connected between a plurality of subscriber terminals and a network interface apparatus connected to a network and capable of transferring a signal to a desired destination for accommodating the subscriber terminals, and a relief package for accommodating the subscriber terminals accommodated in a fault package which has failed from among the plurality of subscriber terminating packages, comprising a multi-connection line disposed in the proximity of and connectable to the plurality of subscriber terminating packages, and a common section for controlling a plurality of connection/disconnection switches carried on the plurality of subscriber terminating packages, the plurality of subscriber terminating packages including multi-connection switches connected to the subscriber terminals and the multi-connection line for connecting/disconnecting electric signals between the subscriber terminals and the multi-connection line, and subscriber connection switches connected to the subscriber terminals and the network interface apparatus for connecting/disconnecting electric signals between the subscriber terminals and the network interface apparatus in response to connection conditions of the multi-connection switches, the relief package including a relief switch connected to the multi-connection line and the network interface apparatus for connecting/disconnecting electric signals between the multi-connection line and the network interface apparatus.
In the subscriber terminating equipment, if a fault occurs with any of the subscriber terminating packages, then the subscriber terminals accommodated in the fault package are automatically accommodated into the relief package in accordance with switching signals from the common section. Consequently, there is an advantage that subscriber terminals which have been accommodated in a fault package can be relieved without the necessity for manual operation for relief switching upon occurrence of a fault.
The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols.